Motion picture projection apparatus



J. A. LINKS zr'm... xombu PICTURE rnoJsc'rltm APPARATUS July 21, 1942;

Filed Sept. 5, 1939 2 Sheets-Sheet l INVENTORS JUL/4N A. LIN/(.5

JIEOM! P. H5257 BY 1 a 6g 2 ATTORNEYS July 21, 1942. J. A. LINKS ETA L2,290,287

MOTION PICTURE PROJECTION APPARATUS Filed Sept. 5, 1959 2 Sheets-Sheet 2INVENTORS JUL/AN 8.1 INKS JEEOIVE P. HEBST flyqfl ATTORNEYS PatentedJuly 21, 1942 UNITED STATES PATENT OFFICE MOTION PICTURE-PROJECTIONAPPARATUS Julian A. links and Jerome P. Beret, San Francisoo, CaliL,assignors of one-half to Max Jay Hirsch, San mm, Calif. ApplicationSeptember 5, 19:9, No. 293,34:

(:. as-a'i) 6Ciaims.

This invention relates to a moving picture projection apparatus andhasfor one of its objects a more compactly arranged moving pictureprojector and reels therefor than heretofore. Another object of theinvention is a complete prolector, reels and screen all arrangedcompactly in a portable cabinet with the reels disposed adjacent two ofthe sides of the projector in positions at a lower elevation thanheretofore, and I in which they are more nearly within the prolectedarea of the said sides than in the conventional projectors. Stillfurther objects of the invention are improved means for projecting alarger image on a screen positioned relatively close to the projector,without noticeable distortion, and an improved screen for such image.Other objects and advantages will appear in the specification anddrawings.

In the drawings, Fig. 1 is a perspective view of the cabinet containingall the essentials for projection of a relatively large image fromeither eight or sixteen millimeter film.

Fig. 2 is a horizontal sectional view of the apparatus of Fig. 1 takenjust below the top of the cabinet and through the screen and mirror.

Fig. 3 is a horizontal, fragmentary sectional view of a portion of thelower part of the cabinet showing the take-up reel therein in dottedline, and the means for guiding the film thereto and also the means forregulating the speed of the take-up reel.

Fig. 4 is a sectional view of one film guide as seen along line 4-4 ofFig. 3.

Fig. 5 is an enlarged sectional view through the reel mounting shaft forthe take-up reel as seen along the line 5-5 of Fig. 3.

Fig. 6 is a sectional view through the improved projection lens of theprojector.

In detail, the apparatus as illustrated in the drawings comprises agenerally oblong cabinet having a front side I, rear side 2, ends I, 4,and a bottom, section I, which bottom section is relatively shallow,vertically, and carriua bottom I (Fig. 3) with short verticallyextending sides and ends in substantially downward continuation of thesides and ends of the main body of the cabinet. The said bottom sectionis hinged to the lower edge of the rear side 2, as at I (Fig. 1),'fortilting the body of the cabinet at its forward side, upwards, away frmnthe lowersection. The main body section carries a bottom portion 8 (Fig.2) wholly or partially covering the lower section. The bottom sectionand the main body portion of the cabinet arereleasably secured togetherby hooks Q at opposite ends of the cabinet, as indicated in Fig. thuspermittingthe entire cabinet to be lifted and moved about 'as a unitwithout danger of the bottom swinging Open.

0n the bottom 1 of themain body section. is a conventional, verticallydisposed projector it, the one indicated generally inthe drawing being aprojector for home motion pictures, such as for 8 mm. or 18 mm. film.The film drive is conventional, hence is not shown indetail, it beingsufilcient to state that the drive pulley indicated at Ii is connected,by conventional drive connections with the motor, for driving the filmfrom the feed reel past the projection lens, indicated at I2.

Heretofore'the feed reel and take-up reel have been mounted one abovethe other at the forward end of the projector, and since these reels arefrom five to ten inches in diameter, and larger, considerable space isrequired to accommodate the reels in this position. Also, in theprojectors for 8 mm. film, only relatively small reels can be used,hence only short pictures can be shown, and the reels must be frequentlychanged. The arrangement of the feed and take-up reels in this inventionenables long reels orshortreelstobeusedwith theminimum of space requiredfor the same.

Reierring to Fig. 2, the feed reel is indicated at it, rotatably mountedfor rotation on a horisontalshaltllsupportedontherearside 2 oi thecabinet. The position of this reel is sub stantlally alongside one sideof the projector it, so that the bottom of the reel is substantiallyopposite the base of the projector II when a reel, say of about 15inches in diameter, is on the shaft.

From said reel it the film II is led around a guide pulley ll supportedforwardly of the projector from a bracket II that is carried on saidprojector. The film passes over the conventional drive pulley ll, thenbetween the lens I! and the light aperture ll and below. drive pulley Hto a guide pulley 2| over which pulley the film passed downwardly toengagement with another guide pulley 2|.- From said guide.pulley ii thefilm passesthroughanopening ninth'ebottom 8.

A roller 23. guide channel strip 24, and roller 2| are secured topartition 21 in the bottom I of the cabinet guide film ll to reel 1!,the rollers 23, II being at the ends of the strip and the strip beinggiven a half turn (Pig. 3) 00 change h direction of the film. lThe'sides"of the channel strip have inturned flanges to. retain the film in thechannel and the base of the channel is recessed to prevent contactbetween the emulsion on the film and strip in the event the emulsion isfacing the strip (Fig.4) Brackets 26 support the strip on the partitionwith the roller 21ladjacent opening 22 and roller 2! adjacent theperiphery of conventional take-up reel 2! (in dotted line Figs. 2, 3).This take-up reel 29 is horizontally disposed, and carries a taperedcentral bearing 2! (Fig.6) adapted to frictionally fit over the taperedupper end 80 of a vertical shaft 2i. Secured at the lower end of saidend 32 is a horizontal disk 32 adapted to support the reel 29 againstany tendency to wobble.

The shaft 2| is driven by a motor 32 through gearing 24 and the speed ofshaft 8| is controlled by a centrifugal governor fl that is in drivingconnection with the drive shaft II through gearing 2'. Disk 21,connected with the axially movable hub of the governor, is adapted to beengaged by a felt or leather brake 28 supported on one arm SI of amodified ball crank, the other arm ll of which crank is held by a springll against a cam 42 secured on a shaft. that rotatably extends throughthe forward wall of the bottom section I. A knob 44 is secured to theend of shaft 42 that projects outwardly of said section 8, which knobcarries a pointer 45 adapted to scan indicia, indicated at 48 in Fig. l,for indicating the desired control for the speed of the take-up reel 28.Upon rotating the knob 44 in one direction, the low side of cam 42 willengage arm ll, thus decreasing the resistance on motor I2, andincreasing the speed of reel 29 for driving say 34 frames per second, orby turning the cam so its high side engages arm. 40 the speed may bereduced for driving, say 15 frames per second. By turning the cam topositions where the arm 4| is engaged between the high and low sides,other speedsbetween the fastest and slowest speeds may be procured. Infact any desired speed between high and low can be accurately andpositively obtained.

In order to compensate for the difference in the speed of the film onthe takeup reel at the hub and adjacent the periphery, the said hub isnicely fitted on the end 2| of shaft Ii to permit slippage between thehub and end 2| when the tendency of the reel is to draw the film fromthe drive pulley Ii on the projection at a rate of speed faster thanthat at which said pulley draws the film from the feed reel. The desiredspeed of driving the reel 2| at the circumference of the filmsupportingportion 41 of reel 28 (Fig. 5) is substantially equal to thespeed at which the pulley, ii feeds the film past the projector.Thereafter, as the film winds on reel 2! to a sufiicient degree, whichis only noticeable in the larger diameter reels, the slippage betweenportion 3| and hub 2! will In order to remove and to replace a reel inthe bottom section I, it is only necessary to tilt the main bodyupwardly, and conventional pivotally stop links 40 (indicated in dottedline in Fig. 1), that connect between the body of the cabinet and thebottom, will support the main body against accidental tilting at toogreat a degree, and such links will likewise support the cabinet intilted position against failing, until the links are collapsed in theusual manner.

Forwardly of the lens l2 and across the corner of the cabinet at thejuncture of end 4 and rear side 2, we posi ion a fiat mirror 52, whichmirror is disposed in a vertical plane at a subtsantially 45' angle tothe central axis of the lens. In the forward side I of the cabinet is anopening 5|,

and just inside said opening is a fiat, translucent, or frosted screen82, which screen may be of glass or Celluloid, or the like. This screen52 is planar sided, but is curved in the direction of its horizontalwidth, the degree of said curvature being substantially that of thecurvature of the field projected by lens i2, indicated in Fig. 2 at X.The area of screen is of course larger than the area of the mirror 52,and is approximately 10 x 12 inches, which is substantially th actualsize of the image projected from an 8 mm. film positioned a total ofonly about 24 inches from the projection lens I2 to said screen by wayof the mirror. The size of the main body of the cabinet itself is onlyabout 15" x 24" x 15''. Thus it will be seen that a greatly enlargedimage is produced on the screen 62 (which image is viewed from the frontof the cabinet), although the actual distance of the film from theprojector is appreciably less than is usual for even a smaller image.

The opening it is adapted to be closed by swinging doors 5: hinged at 84to opposite lateral edges of the opening.

One of the features that enables the large image onscreen 82 within theshort distance of the latter from the projector, is the lens assembly12. This assembly comprises a pair of piano-convex lens 55 each with abi-convex lens 58 cemented in the usual manner in the concave side ofone of the piano-convex lens. The piano-sides of the piano-convex lensface outwardly in the barrel 5'! with one of the convex sides of thebi-convex lens facing toward each other. This type of lens is generallyknown as a wide angle lens, and provides for an appreciably enlargedimage, with inappreciable distortion, which is less as the distancebetween the lens and the screen is increased. The short distance betweenthe screen and lens, in our cabinet, makes it desirable, however, tocurve the screen, as already described.

In order to provide access to the projector and feed reel, in thecabinet, the top of the cabinet is cut away and a hinged lid 58 isprovided (Fig. 1), which lid may be swung on hinges S9 to over theremainder of the top 2. Thus all the working parts of the projector, aswell as the reel H are accessible to an operator.

The bottom section I also provides ample space at the side of thepartition 21 opposite reel 29 for storing extra reels, indicated indotted line at 80, in Fig. 2.

Where small 8 mm. film is used, the take-up reelis, of course,relatively small as compared with the reels I 3, 28, in which case, thebody portion of the cabinet is complete in itself for the take-up reel,in which case, said reel, indicated'at ii is mounted alongside theprojector Ill, opposite the side facing the reel l2. The film i 5, uponleaving pulley 2| in this latter instance, is conducted over pulley 62,that is secured to the lower portion of end 2, and from pulley 62 saidfilm is carried upwardly and over pulley 62 secured to the same side 2near the top and adjacent front wall I. From pulley 62 the film(indicated in dotted line at I 5') is passed over reel SI for winding onthe latter. The reel I is driven by a motor N, the said reel being afriction fit on shaft Iii, but capable of slipping relative to saidshaft in the event of excess tension on the film.

It is accordingly seen from the foregoing that provision is made in ourdevice for extra large reels as-wellas for the smaller reels, and yetthe entire projection equipment, including the screen, is containedwithin a small cabinet. Also, our arrangement enables the projection onsaid screen ofa much larger image than heretofore considering the sizeof the film.

The power for the light-and motors may be supplied through the usualplug ,to the apparatus controlled by suitable switches 61 and a rheostat68 on the end :8 or in any other desired location, but preferablyaccessible outside the cabinet.

Having described our invention, we claim:

1. Apparatus of the character described, com prising an elongated,oblong cabinet with vertical lateral sides having therein asubstantially vertical, flat, reflector and a substantially vertical,rectangular screen of light transmitting material respectively disposedat opposite sides of said cabinet at one end thereof; a motion pictureprojector within said cabinet at the opposite end having a projectionlens arranged to project rays of light forming a picture generallyhorizontally directly onto said reflector for reflection from the lattergenerally horizontally directly onto said screen, said screen and saidreflector and said projector being positioned at generally the samehorizontal level whereby said screen and said reflector are horizontallyoilset relative to said projector to positions entirely removed fromheat rising from said projector; a rectangular opening formed in theside wall of said cabinet opposite said reflector substantially thewidth of said latter wall in direction of its shorter dimension and saidscreen being substantially the same size as said opening and beingsecured in the latter; a horizontal reel for receiving motion picturefilm from said projector after movement of such film past said lens;said reel being positioned below said projector and within the confinesof said cabinet.

2. A device of the character described, comprising, a cabinet havinglateral side walls, a

motion picture projector in said cabinet havinga projection lensarranged to project rays of light generally laterally across theinterior of said cabinet and formed to project said rays substantiallydivergently therefrom, one of said lateral side walls being formed withan opening therein, and a generally rectangular, substantially verticalscreen positioned in said opening, a flat light reflector positionedwithin said cabinet to receive said rays directly from said lens and todirectly reflect said rays onto the side of said screen facing into saidcabinet, said screen bein a sheet light transmitting material curvedhorizontally with the said side thereof facing into said cabinet beingthe concave side of said screen and the curvature of said screencorrespondingto the curvature of the field of said lens whereby thehorizontal distortion of the picture resulting from the divergence ofsaid rays, and observable only on the opposite convex side of saidscreen outside said cabinet by an observer outside said cabinet will bematerially rectified, the relation between said lens, reflector andscreen and the refractive characteristics and form of lens being suchthat the horizontal dimension of the image received on said screen isequal to substantially one-half of the total length of travel of therays from said lens to said screen.

3. A device of the character described, comprising, a cabinet havinglateral side walls, a motion picture projector adjacent one of saidlateral sides and having a projection lens arranged 'to project rays oflight generally horizontally across the interior of said cabinet, saidlens being a wide-angle lens whereby the opposite outside rays, relativeto the central axis of said lens, are projected from said lens at arelatively wide angle, one of said lateral side walls being formed withan opening therein, and a substantially rectangular, substantiallyvertical screen positioned in said opening, a light re, fiectorpositioned within said cabinet adjacent the side wall opposite the saidone of said lateral sides to reflect said rays transversely across theinterior of said cabinet and onto the side of said screen facing intosaid cabinet, said screen being a sheet of light transmitting sheetmaterial curved horizontally with its concave side being said sidefacing into said cabinet, the degree of said curvature of said screenbeing such that the rays of light in a medial plane horizontallydividing the field of rays projected from said lens and reflected bysaid reflector will be of substantially equal length from said lens tosaid screen thereby rectifying the distortion of the picture on saidscreen when the latter is observed from outside said cabinet in viewingthe convex side of said screen, and also materially equalizing thebrilliancy of said picture at all points thereof.

4. In motion picture apparatus of the character described including acabinet enclosing a motion picture projector having a projecting lens, astrip of motion picture film movable pasteach lens, a screen positionedto receive rays of light projected by said lens, a reel positioned toreceive the said film in the form of a coil upon movement of said fllmthrough the projector and past said lens, and means for so moving saidfilm and for revolving said reel; a film guide extending from said reelfor guiding" film thereto, said guide comprising a channel stripslidably supporting said strip of film between the sides of said channelfor longitudinal movement longitudinally of said channel, the bottom ofsaid channel :being longitudinally recessed a width to clear the portionof said strip of film between the opposite longitudinally extendingmargins thereof while slidably supporting said margins at opposite sidesof the recess in said bottom, whereby the portion of the film carryingthe image to be projected by said lens will be free from engagement withsaid channel strip during sliding movement along said strip, and thesides of said channel strip having flanges secured thereto, said flangesextending toward each other and over only the opposite longitudinallyextending margins of said strip of film.

5. In a construction as defined in claim 2, said reel being positionedhorizontally below said projector and lens, and rollers rotatablysupported on opposite ends of said channel strip for supporting saidfllrn upon its entering and leaving the latter, said channel strip beingcurved longitudinally with one of its end portions extending upwardlytoward said lens and with its opposite end portion substantiallyhorizontal and planar with said reel whereby the said strip of filmcarried thereby will be curved corresponding with the curve of saidchannel strip during its longitudinal movement along said strip, andmeans supporting said channel strip stationary relative to saidprojector and said reel.

6. A device of the character described comprising, a cabinet enclosing amotion picture projector having a wide-angle projection lens withrespect to ordinary motion picture projection lens and one reflector, ahorizontally curved screen oi light transmitting sheet materialsecuredinanopeninginoneoithelateralwalls of said cabinet positioned withits concave side facing into said cabinet and its convex side racinzoutwardly: said reflector being the only reflector in said cabinet, andsaid projection lens, reflector and screen being podtioned relative toeach other for projection of the image from said projector directly ontosaid reflector and for reflection oi the said image directly from saidreflector onto said screen with the said image so projected andreflected substantially cover- 5 ing said screen.

JULIANLLINKB. JEROME P. HERST.

